Not only is it stupid and annoying to the people it happens to (or worse), it takes finite resources away from actual threats.
Surely anyone can see that there has to be a line drawn somewhere; that some reporting is utterly frivolous. Why defend the frivolous reporting? Someone scribbling ANYTHING while sitting on a plane is not equivalent to white powder, an unattended package, or a threat. It is what most of us do, at some point or another.